MT#62181 use references instead of copies

Change-Id: I4ba9d630d8896a4b4a83eb47a3678808a2a66869
Warned-by: Coverity

apps/sbc/RegisterCache.cpp

@@ -413,7 +413,7 @@ void _RegisterCache::update(long int reg_expires, const AliasEntry& alias_update
 	}
 
 	// relink binding with the new index
-	auto binding = binding_it->second;
+	auto& binding = binding_it->second;
 	reg_cache_ht.erase_binding(aor_e_it, binding_it);
 	binding_it = aor_e_it->second.insert(make_pair(idx, binding)).first;
       }

apps/sbc/RegisterCache.h

@@ -239,7 +239,7 @@ public:
   string ip;
   unsigned short port;
 
-  ContactKey(string _uri, string _ip, unsigned short _port)
+  ContactKey(const string& _uri, const string& _ip, unsigned short _port)
     : uri(_uri),
       ip(_ip),
       port(_port)